An optoelectronic component (e.g. an organic light emitting diode (OLED)) on an organic basis is usually distinguished by a mechanical flexibility and moderate production conditions. Compared with a component composed of inorganic materials, an optoelectronic component on an organic basis can be produced potentially cost-effectively on account of the possibility of large-area production methods (e.g. roll-to-roll production methods).
Therefore, optoelectronic components on an organic basis, for example OLEDs, are being increasingly widely used and can be employed for the illumination of surfaces. In this case, a surface can be understood for example as a table, a wall or a floor.
An organic optoelectronic component, for example an OLED, may include an anode and a cathode with an organic functional layer system therebetween. The organic functional layer system may include one or a plurality of emitter layer/s in which electromagnetic radiation is generated, one or a plurality of charge generating layer structure each composed of two or more charge generating layers (CGL) for charge generation, and one or a plurality of electron blocking layers, also designated as hole transport layer(s) (HTL), and one or a plurality of hole blocking layers, also designated as electron transport layer(s) (ETL), in order to direct the current flow.
In an OLED, the light generated thereby is partly coupled out directly from the OLED. The rest of the light is distributed into various loss channels, as is illustrated in an illustration of an OLED 100 in FIG. 1. FIG. 1 shows an organic light emitting diode 100 including a glass substrate 102 and a transparent electrode layer 104 composed of indium tin oxide (ITO) arranged thereon. An organic emitting layer 106 is arranged on the electrode layer 104. A second electrode layer 108 composed of a metal is arranged on the organic emitting layer. An electric current supply 110 is connected to the electrode layer 104 and to the second electrode layer 108, such that an electric current for generating light flows through the layer structure arranged between the electrode layers 104, 108.
In organic light emitting diodes, without technical aids a large part of the light (approx. 75%) is lost within the component, for example on account of reflection of a part of the generated light at the interface between the glass substrate 102 and air (symbolized by an arrow 112) and on account of reflection of a part of the generated light at the interface between the first electrode layer 104 and the glass substrate 102 (symbolized by a second arrow 114). That part of the generated light which is coupled out from the glass substrate 102 through the substrate surface provided for coupling-out (the emitted light) is symbolized by a third arrow 116 in FIG. 1.
The generated light that is not coupled out via the substrate surface can be made usable by the two approaches of external and internal coupling-out: solution approaches for eliminating this problem are based on increasing the external coupling-out, which can be achieved by modifying the outer side of the substrate glass up to 50% coupling-out efficiency.
External coupling-out device or structure here shall denote devices or structures which increase the proportion of the light which is coupled out from the substrate into emitted light. Such devices or structures or methods for producing such structures may be:    (a) films having scattering particles on the outer side of the substrate;    (b) films having surface structures (e.g. microlenses);    (c) direct structuring of the outer side of the substrate;            (d) introduction of scattering particles in the glass.        
Some of these approaches (e.g. scattering films) have already been used in OLED lighting modules, or the upscaleability thereof has been shown. However, increasing the external coupling-out has two major disadvantages:    1. The coupling-out efficiency is limited to a maximum of 50% (on account of the jump in refractive index between the organic emitting layer or organic functional layer structure (for short: organic system) or the transparent electrode and glass).    2. The modification of the outer side disadvantageously alters the appearance of the OLED, since the high-quality (polished) glass surface is lost.
This does not suffice for high-efficiency OLEDs, however, and it is desirable to enable so-called internal coupling-out. In the case of internal coupling-out, the light guided in the organic system and the transparent electrode layer is coupled out into the substrate. By increasing the internal coupling-out, it is theoretically possible to couple out up to 80% of the generated light.
However, increasing the internal coupling-out is very complex. There are a number of known technological approaches, although they are not yet being used in OLED products. Such approaches include, for example:    (1) Sun and Forrest describe in Nature Photonics 2, 483 (2008) so-called low-index grids. The latter consist of structured regions including a material having a low refractive index which are applied on the transparent electrode.    (2) US 2007/0257608 describes high refractive index scattering layers below the transparent electrode in a polymeric matrix or in an additionally inserted high refractive index glass layer. In this case, high refractive index denotes a higher refractive index than the glass substrate.    (3) Do et al. describe in Advanced Materials 15, 1214 (2003) so-called Bragg gratings or photonic crystals having periodic structures in the range of the wavelength of visible light.
All the known methods for internally coupling out light constitute a high outlay in terms of process engineering.